Tamper proof seals

ABSTRACT

A tamperproof seal of the type comprising a wire shackle which in use is passed through a loop on an article, and a plastic housing which lockingly receives the ends of the shackle. At least one of the shackle ends has a barb which engages a side wall of a passage in the housing, the other end being similarly or otherwise anchored in the housing. By this invention the housing has a further wall spaced from the said wall on the side thereof remote from the barb, the spacing being such that should the barb perforate the said wall, the amount of the barb, if any, which can perforate the further wall, if cut off, is insufficient to permit that end of the shackle to be pushed back into the passage then simply withdrawn. The space is to narrow for a cutting or welding tool to pass along it. The two limbs are conveniently substantially identical, and the housing a symmetrical one piece plastics moulding.

United States Patent Fernberg et al. Oct. 1, 1974 TAMPER PROOF SEALS 3,485,521 12/1969 Moberg 292/320 [75] Inventors' 22 2 Primary Examiner-Richard E. Moore Harrow, both of England [57] ABSTRACT [73] Asslgnee' L g Buckmghamshlre A tamperproof seal of the type comprising a wire ng an shackle which in use is passed through a loop on an [22] Filed: May 29, 1973 article, and a plastic housing which lockingly receives 1 the ends of the shackle. At least one of the shackle [21] Appl' 364395 ends has a barb which engages a side wall of a passage in the housing, the other end being similarly or other- [30] Foreign Application Priority Data wise anchored in the housing. By this invention the May 25, 1972 Great Britain 24732/72 housing has a further Wall Spaced from the Said Wall on the side thereof remote from the barb, the spacing 52 us. c1. 292/318, 24/303 R being Such that Should the bath perforate the said 51 Int. c1 B65d 33/34 Wall, the amount of the barb if any, which can P [58] Field of Search 292/318, 320, 321; rate the further wall, it Cut Off, is insufficient to Permit 24 305; 243 7 3 74 PB that end of the shackle to be pushed back into the passage then simply withdrawn. The: space is to narrow 5 References Cited for a cutting or welding tool to pass along it. The two UNITED STATES PATENTS limbs are conveniently substantially identical, and the 2 006 042 6/1935 Diem 292/320 X housmg a symmetncal one piece plast1cs moulding Moberg 292/320 10 Claims, 3 Drawing; Figures PATENTED 0371 974 TAMPER PROOF SEALS This invention relates to the type of seal which has a stiff, resilient wire serving as a shackle or loop captured securely within a cavity in a housing to close and lock the loop. The general function of the seal is similar to that of a padlock, but differs in that once it has been locked it cannot be opened except by breaking or deforming it in an evident manner. Seals of this type are particularly useful for coin meter covers, although they can be used on such articles as mail bags and containers which require to be transported in the closed condition. They are known as tamper-proof seals.

In one known example of this type of seal an end of the loop is turned back and projects obliquely to define a barb. The end can be passed easily into a cavity in a plastic housing, and the bar thereby holds secure because it engages behind a shoulder within the cavity. The barb impinges a thick inner wall within the housing. It has been found that pulling on the wire loop has caused the barb to become straightened out because the thickness of the wall has given the wall sufficient strength to resist its penetration by the barb. This en ables the wire loop to be removed, the contents of the meter or bag opened and interfered with, and the barb re-bent and pushed back into the plastic housing. The damage to the thick inner wall, because of the resilience of the material, is indistinguishable from its damage from merely normal use.

In another seal of this type the barb impinges a thin outer wall. Purposeful but unwarranted opening of the seal has been possible by pulling on the wire loop so that the barb has perforated and passed through the outer wall, whereupon its end portion could be cut off, and the loop could be removed from the housing by pushing it back into the cavity so that the shortened barb can pass out of the housing normally. The fastener can be repaired by sealing the wall with a hot tool, reforming the barb with a pair of pliers, and remaking the seal.

According to this invention a seal has a housing of plastics material and a shackle of hard wire, the shackle comprising two joined limbs one of which, when the seal is ready for application, is anchored in the housing, the other being free for passing through a fastener on the article to be sealed and carrying a barb which projects back from the free end of the limb; the housing having a passage which, in the fastened condition of the seal, receives the said other limb, the surface of the passage which engages the barb being on a first wall which is thin, and is shaped to co-operate with the barb to resist withdrawal of the limb, there being a second wall which is spaced from the first wall on the side thereof opposite to the barb, whereby the space between the first and second walls receives the end of the barb in the event that the shackle is pulled sufficiently for the barb to perforate the first wall, the space being such that if the barb perforates the second wall the amount which can then be cut off the barb is insufficient to permit it to be simply withdrawn from the passage.

By describing the first wall as thin, it is intended that the wall should be of a thinness which permits the barb to pass through it without bending, rather than resist the penetration sufficiently to cause the barb to deform.

If the shackle is pulled, the barb will perforate the first wall, which is inaccessible and cannot be repaired.

If the barb is long enough to perforate the second wall, the amount projecting, when cut off, will be insufficient to permit the rest of the barb to be simply withdrawn from the passage. Preferably, however, the barb is not long enough to pass through the second wall.

A seal embodying this invention is described below with reference to the accompanying sketch, in which:

FIG. 1 is an axial section showing the seal ready for application;

FIG. 2 is an axial section similar to FIG. 1 but showing the seal in its sealed condition; and,

FIG. 3 is a perspective view of the seal in the sealed condition.

The seal consists of a shackle 10 which is of a hard ened steel wire. Its shape is best seen in the FIGS. 1 and 2. It consists of a long anchor limb l2 and a slightly shorter fastening limb 14, both limbs attaching to an intermediate body 16 which has three weakenedportions at points marked 18. The purpose of these is described below.

The seal also comprises a housing or body, of poly propylene or nylon, for example, which is shaped to define a thick central inner wall 20, two cavities 22 on each side of the wall, thinner first outer walls 24 which have series of depressions 26 over their inner faces, for reasons described below, and second outer walls 28, which are spaced from the first walls 24 by spaces 30, which are closed at their upper ends. The cavities 20 and 22 have a width, being in the direction perpendicular to the paper, which is substantially equal to the diameter of the wire of the loop 10.

The seal is provided by the manufacturer to the user in the condition seen in FIG. 1, namely with the barb of the anchor limb 12 just engaged in the top depression in the cavity 22. In this condition the loop 16 can be flexed to the left, as viewed, to release the fastener limb 14 from the position seen, and the limb can be threaded through the fastening member of a bag or box which it is to secure. The limb 14 can be reinserted into its cavity, as seen in FIG. I, and the entire shackle can be forced along the cavities of the housing to the position seen in FIG. 2, in which the two barbs tightly abut the depressions 26. In this condition the barbs are held in compression by the outer walls 24, so that their points are caused to dig into the outer walls. Angled portions 32 of the two limbs pass obliquely across the ends of the cavities and make it difficult to insert a tool.

From this condition any attempt to manually pull the loop from the housing will probably lead to breakage of the loop at one of the three weakened points 18, particularly the upper one which is at the apex of a downwardly bent V. If the loop did not break, one or both of the barbs would easily pierce and pass through the associated inner wall 24 because the wall is not strong enough to resist penetration of the: barb. Neither of the barbs is long enough to pass across the space 30 and through the outer walls 28. The space 30 is not large enough to permit a tool to be inserted in to cut the end of the barb. If the loop were pushed back into the cavities to try to conceal the attempted opening, it would not be possible to repair the perforated walls 24 because no tool can be inserted into the spaces 30.

Projecting from an upper edge of the housing is a flange 34, the purpose of which is to thicken the housing sufficiently to prevent it passing through a given size of hasp on a truck tail-board. The flange also serves as a means for facilitating stacking a series of housings in face to face contact. One strip of adhesive tape along a side of the stack bonds to a side edge of each of them. The stack can thereby be readily despatched and used in numerical order, to make theft detectable.

In an alternative seal, not shown, the anchored limb is firmly secured in the material of the housing by moulding or adhesion. The barb projects inwards of the housing and the two spaced walls are in the interior of the housing. a

The two limbs and their barbs could lie adjacent and parallel along their lengths, and be insertable into a single cavity or into two cavities which lie adjacent and parallel, rather than lying coplanar, as is the case in the seal shown.

In a further modification the housing has the form of a sleeve, open at both ends, but having a very narrow elongate bore which tightly accommodates the barbs in its opposite ends. The barbs can impinge the same one edge of the housing, having spaced first and second walls. This shape of housing can be formed by extrusion.

We claim:

1. A seal comprising a plastics housing and a hard wire shackle, the shackle comprising a first limb, which is anchored in the housing, and a second limb which is free for passing through a loop on an article to be fastened, the second limb carrying a barb which projects back from the free end of the limb; the housing having a passage which, in the fastened condition of the seal receives the free end of the second limb, the surface of the passage which engages the barb being on a first wall which is thin and which is shaped to cooperate with the barb to resist subsequent withdrawal of the limb, there being a second wall which is spaced from the first wall on the side thereof opposite to the barb, the spacing and positioning being such that even if the barb perforates the second wall, the amount which can then be cut off the barb is insufficient to permit the second limb to be simply withdrawn from the passage.

2. A seal according to claim 1 in which the first limb of the shackle also has a barb projecting back from its free end.

3. A seal according to claim 2 in which the two barbs project outwards of the shackle.

4. A seal according to claim 2 in which the first limb is longer than the second limb.

5. A seal according to claim 2 in which the two limbs are joined by a loop integral with the limbs and which has at least one weakened portion.

6. A seal according to claim 1 in which the first wall has a series of projections for engaging the barb.

7. A seal according to claim I in which at least the second limb has an angled portion which closes its respective passage when the barb is fastened therein.

8. A seal according to claim 2 in which the housing has two passages for respectively receiving the two limbs of the shackle.

9. A seal according to claim 8 in which the two passages are sealed at their one end.

10. The seal comprising a one-piece plastic housing having a pair of axially extending passages opening through one end of the housing and a hard wire shackle, the shackle comprising a first limb which is anchored in the housing in one of said passages, and a second limb which is free for passing through a loop of an article to be fastened, said second limb carrying a barb which projects back from the free end of the limb, the second passage of said housing being adapted to receive the free end of the second limb in the fastened condition of the seal, the surface of the passage which engages the barb, being on a first wall which is thin and which is shaped to cooperate with the barb to resist subsequent withdrawal of the limb, said housing including along a substantial portion of each edge thereof an integral shroud open at one end and providing a second wall which is spaced from the first wall on the side thereof opposite to the barb, the spacing and positioning being such that even if the barb perforates the second wall, the amount which can then be cut off the barb is insufficient to permit the second limb to be simply withdrawn from the passage, the spacing between said walls being such as to prevent insertion of a tool into such space. 

1. A seal comprising a plastics housing and a hard wire shackle, the shackle comprising a first limb, which is anchored in the housing, and a second limb which is free for passing through a loop on an article to be fastened, the second limb carrying a barb which projects back from the free end of the limb; the housing having a passage which, in the fastened condition of the seal receives the free end of the second limb, the surface of the passage which engages the barb being on a first wall which is thin and which is shaped to cooperate with the barb to resist subsequent withdrawal of the limb, there being a second wall which is spaced from the first wall on the side thereof opposite to the barb, the spacing and positioning being such that even if the barb perforates the second wall, the amount which can then be cut off the barb is insufficient to permit the second limb to be simply withdrawn from the passage.
 2. A seal according to claim 1 in which the first limb of the shackle also has a barb projecting back from its free end.
 3. A seal according to claim 2 in which the two barbs project outwards of the shackle.
 4. A seal according to claim 2 in which the first limb is longer than the second limb.
 5. A seal according to claim 2 in which the two limbs are joined by a loop integral with the limbs and which has at least one weakened portion.
 6. A seal according to claim 1 in which the first wall has a series of projections for engaging the barb.
 7. A seal according to claim 1 in which at least the second limb has an angled portion which closes its respective passage when the barb is fastened therein.
 8. A seal according to claim 2 in which the housing has two passages for respectively receiving the two limbs of the shackle.
 9. A seal according to claim 8 in which the two passages are sealed at their one end.
 10. The seal comprising a one-piece plastic housing having a pair of axially extending passages opening through one end of the housing and a hard wire shackle, the shackle comprising a first limb which is anchored in the housing in one of said passages, and a second limb which is free for passing through a loop of an article to be fastened, said second limb carrying a barb which projects back from the free end of the limb, the second passage of said housing being adapted to receive the free end of the second limb in the fastened condition of the seal, the surface of the passage which engages the barb, being on a first wall which is thin and which is shaped to cooperate with the barb to resist subsequEnt withdrawal of the limb, said housing including along a substantial portion of each edge thereof an integral shroud open at one end and providing a second wall which is spaced from the first wall on the side thereof opposite to the barb, the spacing and positioning being such that even if the barb perforates the second wall, the amount which can then be cut off the barb is insufficient to permit the second limb to be simply withdrawn from the passage, the spacing between said walls being such as to prevent insertion of a tool into such space. 